The invention relates to bushings, and especially to slipper bushings which are mainly used in automobile suspension systems to provide relative rotation or slippage between rigid inner and outer sleeves of the bushing. This is conventionally accomplished by using a resilient, tubular rubber insert or sleeve which is bonded or press fitted to one of the metal sleeves.
U.S. Pat. Nos. 3,171,699, 3,215,477, 3,300,257, 4,671,678 and 5,100,114 are typical of the many patents relating to simple bushings which employ a resilient elastomeric insert, with or without metal reinforcement, between rigid, inner and outer metal sleeves. U.S. Pat. Nos. 4,744,677, 4,767,108 and 4,809,960 relate to more sophisticated bushings.
U.S. Pat. No. 5,139,244 discloses a unique slipper bushing which essentially comprises; (i) a hollow, cylindrical, inner metal sleeve, (ii) a specially shaped, resilient elastomeric insert or sleeve which is force fitted around the inner metal sleeve, (iii) an outer polymeric sleeve which surrounds the elastomeric sleeve in abutting relation, such that relative movement between the elastomeric and polymeric sleeves can occur, (iv) a lubricant between the interfaces of the elastomeric and polymeric sleeves to facilitate such relative movement, and (v) a pair of hollow, metal end caps force fitted to the opposing ends of the inner metal sleeve. The slipper bushing has good performance characteristics. However, it has been found that under very severe loading, the elastomeric sleeve becomes axially distorted or tends to extend over the end caps at its opposing ends, to adversely affect operation of the bushing. The slipper bushing of this invention is designed to eliminate or substantially reduce this problem by providing a structure with a highly improved capacity for resisting lateral or axial loads without becoming distorted excessively.
Briefly stated, the invention is in a slipper bushing which essentially comprises a hollow, rigid, cylindrical inner sleeve, a polymeric sleeve secured around the inner sleeve, a resilient elastomeric insert or sleeve surrounding the polymeric sleeve in abutting relation therewith, a lubricant between the abutting interfaces or surfaces of the polymeric and elastomeric sleeves, a rigid outer sleeve to which the polymeric sleeve is mold bonded and a pair of rigid, hollow end caps for sealing the opposing ends of the bushing, especially the lubricated interfaces between the polymeric and elastomeric sleeves. The lubricated interfaces are Provided with a plurality of circumferentially oriented grooves in which the lubricant is free to move in and out of.
It can be appreciated from the above brief description that the highly deformable resilient elastomeric sleeve is bonded to the rigid outer sleeve, to resist the distortion caused by lateral and axial loads contrary to my aforementioned '244 patent where the resilient elastomeric sleeve is secured to the rigid inner sleeve.